This invention relates to an electrical connector and, in particular, to an electrical connector which is to be mounted on a circuit board and which includes an engaging member for electrically connecting the electrical connector and the circuit board and for mechanically engaging the electrical connector with the circuit board.
A conventional electrical connector comprises an insulator and a plurality of electroconductive contacts fitted into the insulator. The insulator comprises a base portion and a pair of blocks formed at both ends of the base portion. Each of the contacts has a support portion supported by the base portion, a contact portion connected to one end of the support portion, and a terminal portion connected to other end of the support portion. The contact portion outwardly extends from a main surface of the base portion. The terminal portion outwardly extends from a subsidiary surface opposite to the main surface. By means of soldering, the terminal portions of a plurality of the contacts are connected in one-to-one correspondence to a plurality of electroconductive pads formed on one or a first surface of a circuit board.
Each of the blocks has a mounting surface to face the first surface of the circuit board. For brevity of the description, one of the blocks is herein referred to because both of the blocks have a similar structure. The mounting surface is provided with a guide projection and a first engaging member in the vicinity of the guide projection. When the mounting surface is mounted to the first surface of the circuit board, the guide projection is inserted into a guide hole formed on the circuit board. The first engaging member comprises a first elastic engagement portion. When the mounting surface is mounted on the first surface of the circuit board, the first elastic engagement portion is inserted into a locking hole formed on the circuit board. Furthermore, the first elastic engagement portion is provided with a first hook portion at a top end thereof. When the first elastic engagement portion is inserted into the locking hole, the first hook portion is brought into contact with the inner wall of the locking hole. The first elastic engagement portion is then elastically deformed and inserted further. Finally, the first hook portion passes through the locking hole and projects onto other or a second surface of the circuit board to be engaged with the second surface of the circuit board.
As described above, the conventional electrical connector has a pair of the blocks each of which is provided with the guide projection and the first engaging member.
In order to meet a demand for accommodating an increased number of the contacts, the base portion must have an increased size in a longitudinal direction to arrange a large number of the contacts.
However, the base portion having such an increased size tends to be bent in an arcuate curve. In this event, the terminal portions are mounted to the pads on the circuit board with gaps left therebetween. As a result, a soldering process is difficult because of presence of such gaps.
In addition, the circuit board is formed of a thin plate. In cases when the circuit board is bent in an arcuate curve, the terminal portions are mounted to the pads on the circuit board with gaps left therebetween like the above-mentioned case. As a result, the soldering process is difficult because of presence of such gaps.
Even on presence of such gaps, it may be possible to connect the terminal portions and the pads on the circuit board by soldering. However, the soldered portions receive a great load due to a force produced by coupling operation between the contact portions and a mating connector. Due to the load, the terminal portions are removed from the pads at the soldered portions. This brings about a connection failure.
Another type of the conventional electrical connector is disclosed in Japanese Unexamined Utility Model Prepublication No. 19281/1991 or Jitsukai Hei 3-19281.
In this electrical connector, a vacant area with no contacts is interposed in an array of a plurality of contacts equally spaced from one another. An engaging pin is made to pass through the vacant area. The top end of the engaging pin is inserted into an engaging hole formed on a circuit board so as to restore the circuit board from a curved shape into a straight shape.
As described above, this electrical connector can restore the circuit board from a curved shape into a straight shape by the use of the engaging pins. However, the engaging pin must be interposed in the array of the contacts to interrupt the array of the contacts. As a result, it is impossible to arrange a large number of the contacts at a high density.